Predictive modelling of hypoxic ischaemic encephalopathy risk following perinatal asphyxia

Hypoxic Ischemic Encephalopathy (HIE) remains a major cause of neurological disability. Early intervention with therapeutic hypothermia improves outcome, but prediction of HIE is difficult and no single clinical marker is reliable. Machine learning algorithms may allow identification of patterns in clinical data to improve prognostic power. Here we examine the use of a Random Forest machine learning algorithm and five-fold cross-validation to predict the occurrence of HIE in a prospective cohort of infants with perinatal asphyxia. Infants with perinatal asphyxia were recruited at birth and neonatal course was followed for the development of HIE. Clinical variables were recorded for each infant including maternal demographics, delivery details and infant's condition at birth. We found that the strongest predictors of HIE were the infant's condition at birth (as expressed by Apgar score), need for resuscitation, and the first postnatal measures of pH, lactate, and base deficit. Random Forest models combining features including Apgar score, most intensive resuscitation, maternal age and infant birth weight both with and without biochemical markers of pH, lactate, and base deficit resulted in a sensitivity of 56-100% and a specificity of 78-99%. This study presents a dynamic method of rapid classification that has the potential to be easily adapted and implemented in a clinical setting, with and without the availability of blood gas analysis. Our results demonstrate that applying machine learning algorithms to readily available clinical data may support clinicians in the early and accurate identification of infants who will develop HIE. We anticipate our models to be a starting point for the development of a more sophisticated clinical decision support system to help identify which infants will benefit from early therapeutic hypothermia.

A study of "white spotted kidneys" in cattle

A study was performed at an abattoir in Australia, in an attempt to correlate focal chronic interstitial nephritis (FCIN) producing the so-called "white spotted kidney", with Leptospira spp. and other pathogens in cattle. Samples of kidneys, urine and blood were collected immediately after slaughter from 46 two-year-old heifers, and 72 cows and bulls with gross lesions consistent with FCIN. The same samples were also collected from nine heifers and 12 cows with no gross kidney lesions. Aqueous humour was also collected from the eye of 17 of the adult animals. The sera were processed by a microscopic agglutination test for leptospira antibodies, while all the other samples were cultured for Leptospira spp. and also processed for routine aerobic and anaerobic culture for other pathogens. Sub-samples from all the kidneys were fixed in 10% buffered formalin and processed histologically. Antibody titers of 1:400 or higher for Lepstospira borgpeterseni serovar hardjo were found in six adult animals with FCIN and in one adult animal with no gross kidney changes, while antibody titers of 1:400 to L. borgpeterseni serovar tarassovi were found in only one animal with FCIN. L. borgpeterseni serovar hardjo was isolated from the urine and kidney of one adult animal and from the urine of another adult animal, both with FCIN. No pathogens were isolated from any of the other samples. The histological lesions were consistent in most cases with FCIN. The results suggest that neither Leptospira spp. nor active infection by other bacteria are associated with the so-called "white spotted kidneys".

The burns unit and theatre integration

Disbanding the assigned burns theatre team at St John's Hospital had a major impact on perioperative care. Donna O'Boyle describes how, and what was done to rectify the situation, in her 3M/NATN Award commended work.

The molecular epidemiology of four outbreaks of porcine pasteurellosis

Biochemical profiles, restriction endonuclease analysis (REA) and ribotyping were used to investigate a total of 38 Pasteurella multocida isolates from four separate outbreaks of pasteurellosis in Australian piggeries. Six isolates were obtained from Outbreak 1, 16 from Outbreak 2 and eight each from outbreaks 3 and 4. Outbreaks 1 and 2 were cases of pneumonic pasteurellosis while outbreaks 3 and 4 involved systemic pasteurellosis. Biochemical characterisation established that a number of different types of P. multocida were present in outbreaks 1 and 3 while outbreaks 2 and 4 were associated with a single type of P. multocida. Outbreaks 1 and 3 yielded isolates of P. multocida that belonged to the subspecies multocida and gallicida, with the subspecies multocida isolates being identified as biovar 3 (6 in total) or 12 (1 in total) and the subspecies gallicida isolates (7 in total) being identified as biovar 8. All 24 isolates from outbreaks 2 and 4 belonged to the subspecies multocida and were all biovar 3. REA and ribotyping showed that, in outbreaks 1 and 3, there were three different types of P. multocida in each outbreak with no common strains between the outbreaks. The molecular methods showed that only a single strain of P. multocida was associated with outbreaks 2 and 4, although the outbreaks were associated with strains that differed in REA profiles but shared a ribotype profile. This study has shown that both, systemic and pneumonic pasteurellosis can be associated with either a single strain or multiple strains of P. multocida. The results also indicate that the molecular typing methods of REA and ribotyping are superior to biochemical characterisation for epidemiological investigation of porcine pasteurellosis.

PCR detection and analysis of Pasteurella multocida from the tonsils of slaughtered pigs in Vietnam

A total of 36 tonsil swab samples were collected from healthy swine prior to slaughter at the abattoirs in Can tho and Tien giang provinces of Southern Vietnam. The presence of Pasteurella multocida in these samples was detected by the combination of direct cultivation and isolation, mouse inoculation and the polymerase chain reaction (PM-PCR). P. multocida was detected in 16 samples by PCR, with 17 strains ultimately isolated. All samples were negative for serogroup B by HSB-PCR and conventional serotyping, with isolates identified as A:3, D:1 or D:3. In addition, all samples were determined to be negative for the P. multocida toxin (PMT). Characterisation of isolated P. multocida by REP-PCR and biotyping revealed nine distinct REP profiles and seven biotypes among the 17 isolates. Some correlation was seen with P. multocida isolated from a previous Australian outbreak of acute swine pasteurellosis, and those isolated from fowl cholera outbreaks in Vietnamese poultry.

The virulence and protective efficacy for chickens of pasteurella multocida administered by different routes

The relative virulence for chickens of five strains of Pasteurella multocida was evaluated. Twenty groups, each of ten chickens, were inoculated with a standard dose of 10(5) of each of five strains by the intramuscular (I.m.), intravenous (I.v.), intratracheal (I.tr.) or conjunctival (Co) routes. The highest mortality occurred in the groups dosed I.m. and I.v., followed by I.tr. inoculation. The relative virulence of each strain did not change when inoculated by the different routes. The most virulent strain, VP161, caused 100% mortality by all except the Co route. The least virulent strain, VP17, caused a single mortality by the I.v. route, but gave a high level of protection to birds inoculated by both the I.m. and I.v. routes, when challenged by intramuscular injection with (VP161). There was no protection against I.m. challenge in the birds inoculated by the I.tr. or Co routes. Serum antibody levels measured by ELISA correlated with the level of protection against virulent challenge for groups inoculated I.m. or I.v., but not I.tr. Western blots of pooled sera from each group did not show any specific antigen recognition that might explain the observed differences in protection. Inoculation with strain VP17, (both I.m. and I.tr.) also gave a high level of protection to birds challenged with strain VP161 by intratracheal instillation.

Joint position sense is impaired by Parkinson's disease

The abilities of Parkinson's disease (PD) patients, taking routine medication, and of control subjects, to discriminate bilateral differences in the static angular positions of the two elbow joints were studied during passive (subject relaxed) and active (subject contracting to hold position) conditions. On each trial, one of the subject's elbows served as the reference joint (angle 60 degrees) and the other as the test joint (angular range, 54 degrees to 69 degrees, at 3 degree intervals). Subjects, with eyes closed, were required to discriminate the relative angles of the two elbows. In Experiments 1 (passive condition) and 2 (active condition), parkinsonians (n = 12) gave significantly fewer correct responses, pooled across sides, than did controls (n = 12), both in total scores across all angles and at individual test angles of 57 degrees and 63 degrees. In Experiment 3 (passive condition), derivation of conventional psychophysical variables indicated that both the difference limen (DL; threshold) and Weber ratio (WR; discriminatory sensitivity, independent of absolute stimulus values; same as DL/PSE) values of patients (n = 6) were significantly larger than those of controls (n = 6), in the absence of a significant difference between groups in the point of subjective equality (PSE). Our results provide clear evidence of a quantitative impairment of joint position sense in PD patients.

Effects of dry cow intramammary therapy on quarter infections in the dry period

Quarter milk samples were taken from 150 cows from three dairy farms in south-east Queensland at drying off, two, four and six weeks after drying off, at calving, and one, two and three weeks after calving. In each of the herds, the cows were randomly allocated to three groups of approximately equal size. One group had all the quarters of all the cows treated at drying off with a dry cow antibiotic infusion containing cloxacillin; the second group was given no treatment, and the third group had selected quarters treated on the basis of their high activity of N-acetyl-beta-D-glucosaminidase at drying off. Dry cow treatment resulted in a marked reduction in the number of infected quarters at two and four weeks after drying off, so that the comprehensively treated group had significantly less infected quarters at these times (P<0.02). Twelve dinical cases of mastitis were detected two weeks after drying off in the untreated groups, 10 in the untreated quarters of the selectively treated groups, and no cases in the comprehensively treated groups. These cases were due mainly to Streptococcus uberis and Streptococcus dysgalactiae. The number of infected untreated quarters increased markedly between drying off and two weeks later, but in all three groups there was a marked decrease in the number of infected quarters between six weeks after drying off and calving, suggesting that the mammary glands were more able to overcome infections at this time.

Acute septicaemic pasteurellosis in Vietnamese pigs

Sixteen isolates of Pasteurella multocida were cultured from cases diagnosed as acute septicaemic pasteurellosis in Vietnamese pigs. The HSB-PCR assay provided rapid presumptive determination of 10 isolates of P. multocida identified as haemorrhagic septicaemia (HS) causing type B cultures (B:2, B:5, B:2,5). Serological designation using the Carter and Heddleston typing systems confirmed these findings, and identified the six HSB-PCR negative cultures as either A:1, A:3 or D:3,4. Biochemical fermentation and REP-PCR revealed phenotypic and genotypic identity between P. multocida type A:1 isolated from Vietnamese pigs and poultry. Marked homogeneity was also demonstrated among HSB-PCR positive swine isolates, which were shown to possess genotypic identity with P. multocida type B:2 from buffaloes diagnosed with HS.

Antibiotics for the preservation of koala (Phascolarctos cinereus) semen

AIM

To determine the normal microbial flora of the koala ejaculate and prepuce in order to select appropriate antibiotics for addition into diluents designed for the preservation of semen.

PROCEDURE

Bacteriological samples of the koala prepuce (n = 12) and ejaculate (n = 20) were submitted for microbial culture and sensitivity testing. Microbial flora of ejaculates collected by electroejaculation and artificial vagina were compared. The effects of varying concentrations of penicillin G and gentamicin on sperm motility and on the growth of bacteria in diluted semen stored at room temperature and 16 degrees C over a 24 h period were investigated.

RESULTS

A range of bacteria was isolated from the koala prepuce and ejaculate. The predominant organisms in semen collected by electroejaculation and artificial vagina were Corynebacterium spp, none of which could be assigned to any recognised species. The addition of penicillin G and gentamicin to a PBS-based diluent at dose rates of 1000 to 2000 IU/mL and 100 to 200 micrograms/mL respectively, resulted in no adverse effect on sperm motility over a 24 h incubation period. Penicillin G (1000 IU/mL) and gentamicin (100 micrograms/mL) prevented growth of bacterial contaminants in diluted koala semen.

CONCLUSION

By controlling the growth of bacteria in extended koala semen, penicillin G and gentamicin are likely to lengthen the period by which spermatozoa can be stored at 16 degrees C and reduce the possibility of disease transmission during artificial insemination procedures.

Detection by polymerase chain reaction of Clostridium perfringens producing epsilon toxin in faeces and in gastrointestinal contents of goats

A polymerase chain reaction (PCR) was used to identify the gene-encoding epsilon toxin production in Clostridium perfringens types B and D in faeces and in gastrointestinal contents of goats. The samples were cultured in thioglycollate broth and centrifuged. The upper layer of the pellet was used as a template for PCR, obviating the need for DNA extraction. This technique specifically differentiated Cl. perfringens types B and D from Cl. perfringens types A and C and from Escherichia coli. When used to identify Cl. perfringens type D in samples artificially spiked with the micro-organism, the PCR detected as few as 1.4 x 10(2) cfu g-1 of sample. Gastrointestinal contents and faeces were collected from 20 goats at slaughter and processed by PCR. Several positive results were obtained from the first five goats that were slaughtered and sampled a few days after their arrival at the abattoir, but only a few samples gave positive results during the following weeks, after the goats had been fed a concentrated ration containing monensin. A possible role of this drug in control of enterotoxaemia is suggested.

In vitro proteolytic activity and active-site identification of the human cytomegalovirus protease

Human cytomegalovirus (HCMV) encodes a protease that cleaves itself and the HCMV assembly protein. Two proteolytic processing sites within the protease were identified at Ala 256-Ser 257 (release site) and Ala 643-Ser 644 (maturation site). Identification of rP5-P4' and mP4-P6' as the minimal peptide substrates spanning the release and maturation cleavage sites, respectively, demonstrated a requirement for residues flanking the conserved core in substrate recognition and hydrolysis, which are unique to HCMV. Kinetic parameters determined for release-site-derived and maturation-site-derived peptides revealed a 10-fold increase in kcat/Km for a maturational peptide (mP4-P8') over release-site peptide (rP5-P5'). Experimental results with a panel of class-specific protease inhibitors were consistent with the protease being a member of the serine or cysteine family of proteases. Further investigation revealed that the HCMV protease activity decreased with incorporation of [14C]iodoacetic acid, but when approximately 4.5 mol 14C were incorporated/mol enzyme, the enzyme retained approximately 20% of its original activity, indicating that hydrolysis does not require a cysteine nucleophile. Analysis of diisopropyl-fluorophosphate-inactivated protease by mass spectrometry indicated a stoichiometry of 1 diisopropyl phosphate/protease molecule, suggesting that hydrolysis requires a single serine nucleophile. The residue modified by diisopropyl fluorophosphate was identified as Ser132 by modification with 3H-labeled diisopropyl fluorophosphate, peptide mapping and Edman degradation. This residue and the region in which it is found is highly conserved among the herpes virus proteases. These data demonstrates that HCMV protease is a serine protease and that Ser132 is the active-site nucleophile.

A study of the microbial flora of the anterior vagina of normal sows during different stages of the reproductive cycle

Sterile guarded swabs were used to sample the anterior vaginal and cervical area of 23 normal healthy sows during various stages of the reproductive cycle. The samples were collected one week before farrowing, within 24 hours of farrowing, weekly up to weaning, at mating and at 2 and 3 weeks after mating, and then plated and incubated aerobically and anaerobically. At least one positive sample was obtained from each sow and at each stage of the reproductive cycle. Most positive samples (78.3%) were obtained on the day of farrowing and the least 3 weeks after mating (19.0%). The second highest number of positive samples (45.5%) was found immediately after mating. Although there was no significant difference among sows of different parities, there was a trend for older sows to have more positive samples after farrowing (84.6%). There was a greater decrease in positive samples after farrowing and after mating among younger sows compared with older sows. A wide range of bacteria including aerobic and anaerobic species, were recovered from 142 isolates. The more representative bacteria were Streptococcus spp (23.2%); Escherichia coli (22.5%); Staphylococcus spp (19.0%) and Corynebacterium spp (13.4%). Of the cultures, 54.7% were pure and 45.3% were mixed. Both the percentage of bacterial isolates as well as the type of culture (pure or mixed) were similar to those frequently reported in clinical cases of vulval discharge syndrome. The results indicate that sows usually develop infections of the reproductive tract at farrowing and mating but these infections do not normally persist.

Establishment of a state-supported, specialized home care program for children with complex health-care needs

Establishment of a systematic approach to home care for children who require complex, technology-dependent care requires a well-thought-out process of collaboration and planning between all parties involved--the family, the professional, and the hospital. The State of Michigan Department of Public Health elected to assist families in taking their children home through a Specialized Home Care Program funded by combined sources that emphasized child care needs first rather than cost savings. This review identifies the development of roles, processes and products, and methods to enhance the discharge planning and home care processes. These processes indicate the need for parent involvement and teamwork with health-care professionals. Refinement of the program is suggested as well as further development of an evaluation component and family assessment tools.

N-acetyl-ß-D-glucosaminidase activity in the endometrial epithelium of the cow's uterus during the oestrous cycle and pregnancy

The levels of N-acetyl-beta-D-glucosaminidase (NAGase) were measured in the endometrial epithelial tissue of the bovine uterus during the oestrous cycle and during pregnancy. NAGase levels were significantly (P<0.001) higher in the epithelial tissue of the cow's uterus during the luteal phase of the cycle and during pregnancy than during the non-luteal phase. There were significantly (P<0.001) higher mean NAGase values in the epithelial than the subepithelial layers of the uterus in the two cycle phases and in pregnancy. Leucocyte numbers were significantly (P<0.05 and P<0.001) higher in the cows' uteri during the non-luteal phase than during the luteal phase and pregnancy, respectively. It is concluded that the endometrial epithelial layer is significantly active in terms of NAGase release and that this may be related to increased progesterone concentrations. In addition, the epithelial tissue (not leucocytes) appears to be the main contributor to the total NAGase activity in uterine tissue.

Postpartum uterine flora following normal and abnormal puerperium in cows

Uterine swabs were taken from the uteri of three groups of cows (n = 5 each) on Days 1 and 2 and then at 3-d intervals up to 32 d post partum. Group I cows had a normal delivery, Group II cows had dexamethasone-induced parturition, and Group III cows were subjected to a Caesarean section. All cows in Group III and two cows in Group II retained their fetal membranes. A total of 230 bacterial isolates were made, and the most frequently isolated bacteria were Escherichia coli, streptococci, Proteus spp., and clostridia. The highest number of bacterial isolates and the longest mean time to complete uterine involution were in the Group III cows.

The growth of Salmonella in rumen fluid from cattle at slaughter

The pH of the rument contents of cattle was recorded at slaughter; pH ranged from 5.5 to 7.8 and was not correlated with the period from saleyard to slaughter. Volatile fatty acids (VFA) were measured in 43 rumen samples; acetic, propionic and butyric were the major acids present, and the total VFA ranged from 75.9 mM/l for samples between pH 6-7, to 7.1 mM/l for samples of pH 8-9. Ten Salmonella strains belonging to 8 serotypes were grown in these 43 rumen samples. Where acid levels of these samples were high and pH low, most Salmonella sp. were inhibited; as the pH rose (pH 7-8) all Salmonella serotypes grew, some vigorously; as the total acid declined and pH continued to rise, growth of salmonella ceased. Serotypes and strains of the same serotype differed in their ability to grow in rumen contents, particularly when the pH was low.

Distribution of lysosomal enzymes within the non-secretory epithelium of the bovine mammary gland

The levels of N-acetyl-beta-glucosaminidase (NAGase) and acid phosphatase were analysed in tissue from the teat and lactiferous sinus epithelia of dairy cows at different stages of lactation. Enzyme levels were lower in the epithelia of the teat sinus than of the lactiferous sinus. For both enzymes, levels were highest in tissue from post-partum glands, lowest in those from dry and mid-lactation glands. In involuting glands the levels were high, but not as high as the post-partum glands.

The growth of compact and diffuse variants of Staphylococcus aureus in bovine mastitic and normal whey

Strains of Staphylococcus aureus producing either diffuse or compact colonies in serum-soft agar were grown in bovine normal and mastitic whey. Bacterial growth was followed by automated turbidometry. Compact strains multiplied faster and to higher final numbers in mastitic whey than diffuse strains, whereas diffuse strains grew to higher numbers in normal whey. Nutrients (hemolysed bovine blood, bovine serum, proteose-peptone) were added to normal whey to enhance bacterial growth as in mastitic whey. The growth-promoting effect of these nutrients was dose-dependent for compact strains but not for diffuse strains. The difference in the growth characteristics of diffuse and compact strains in bovine whey explains some aspects of the pathogenesis of bovine mastitis.

The effect of a staphylococcal cell wall factor on the early inflammatory response to staphylococcal infection of the lactating bovine udder

The effect on the early inflammatory response in the bovine mammary gland of a factor extracted from the cell wall of Staphylococcus aureus was studied. The insoluble factor was extracted from a 3h-culture, and was mixed with S. aureus from an overnight culture (OF) for experimental infection of a lactating quarter. Other quarters were infected with a 3h or an overnight culture (O). Five cows were used in the experiment. The O-quarters showed more severe clinical signs than seen in the 3h-and OF-quarters. Antitrypsin levels and NAGase concentrations were much reduced in the 3h-and OF-quarters. While the cell wall factor profoundly reduced the early inflammatory response, the effect on the final outcome of the infection was not determined.

Specificity of the anti-inflammatory effect of a staphylococcal cell wall extract in the bovine udder

The cell wall of Staphylococcus aureus (strains 21 and Glaxo) was treated with deoxycholate and the insoluble residue was solubilised with lysozyme. The effect of the extract in modulating the inflammatory response due to infection of the lactating bovine udder was evaluated. Cows were infected with S. aureus strain 21 or Streptococcus agalactiae, with or without the cell wall extracts. The clinical response to infection was assessed, and milk samples collected up to 30 h were assayed for antitrypsin and NAGase levels, somatic cell count, and for the ability of whey to support bacterial growth. The extracts markedly reduced the inflammatory response elicited by both S. aureus and S. agalactiae, indicating the effect was non-specific. The extract from strain 21 was generally more effective than that from strain Glaxo.

Adhesion of Staphylococcus aureus and Escherichia coli to bovine udder epithelial cells

An assay for the adhesion of tritiated thymidine-labelled Staphylococcus aureus and Escherichia coli to bovine mammary ductular epithelial cell lines was developed. The relative adhesion of 15 strains of S. aureus to these cell lines was examined. Four strains did not adhere and the remaining 11 adhered at variable levels. Adhesion to different cell lines was generally similar. Adhesion to freshly collected bovine mammary epithelial cells was significantly greater than that to cells maintained in tissue culture. The system described was demonstrated to be a suitable model for studying adhesion of mastitis-causing organisms to bovine mammary epithelial cells.

The expression of capsule in serum-soft agar by Staphylococcus aureus isolated from bovine mastitis

Strains of Staphylococcus aureus were isolated from bovine mastitis, subcultured and maintained in the laboratory for up to 3 years. Encapsulation was assessed by production of a diffuse colony in serum-soft agar. Eight (4%) of 200 strains were encapsulated. Three rapid passages of the remaining 192 strains through either brain-heart infusion broth containing 30% serum or modified 110 medium retrieved the capsule in 75%, but this was rapidly lost after subculture on blood agar. The stimulation of capsule production was studied in 18 of these strains by addition of various components to the passaging medium. Heat-labile factors in serum, milk and mastitic milk enhanced capsule production while bovine serum albumin, an extract of polymorphonuclear leucocytes, NaCl and immunoglobulins had minimal effect. The results indicate that encapsulation is common in bovine staphylococci and while it is lost on subculture, may be retrieved under appropriate conditions.

The expression of capsule in serum-soft agar by Staphylococcus aureus isolated from human clinical sources

Staphylococcus aureus isolates from human clinical sources were incubated for various times in modified 110 medium and tested for production of capsule by the serum-soft agar technique. Ten (5.7%) of 175 isolates were encapsulated after incubation for 24 h. A more detailed examination of 77 isolates showed that incubation period affected the production of capsule. After 2 h, 31% were encapsulated, but after 6 h and 24 h this decreased to 17% and 4% respectively. Rapid passage in vitro induced the expression of capsule in four of 50 unencapsulated strains. Only three of 20 encapsulated strains could be typed with standard antisera.

A survey of clinical mastitis in South-East Queensland dairy herds

A survey if clinical mastitis in 26 South-East Queensland dairy herds supplying more than 300,000 litres of milk annually, revealed a quarter incidence of 2.6% with a cow incidence of 9% over a 3-month period. Secretion samples from cows yielded Staphylococcus aureus, Streptococcus agalactiae, Streptococcus dysgalactiae, Streptococcus Uberis, Coliforms, Pseudomonas spp and other bacteria in 38.5%, 12.5%, 6.6%, 3.4%, 2.6%, 0.6% and 2.0% of cases respectively. Samples from 38% of the cases were culturally negative while at least 38% of the clinical quarters had shown a previous clinical episode of mastitis. There was a significant association (P less than 0.025) between herd and the likelihood of a negative culture result on samples from clinical cases. Twenty-one percent of cases occurred in the first month of lactation and 10.3% in the first week. There was a significant association (P less than 0.005) between the age of cow and the stage of lactation in which clinical cases occurred in that cows in the 2 to 5 year age group were more likely to suffer attacks in the earlier part of lactation. There was a highly significant relationship (P less than 0.005) between cow age group and the proportion of affected quarters and it was calculated that the change with each year of age was a 55% increase over the previous year. Forty-five percent of the isolates of S. aureus were resistant to penicillin.

The resistance to antimicrobial agents of Staphylococcus aureus isolated from the bovine udder

Isolates of Staphylococcus aureus (total 1657) from bovine mastitis were collected from 13 laboratories throughout Australia from 1974 to 1979. They were tested for resistance to antimicrobial agents using an agar dilution method. Resistance shown was mainly to penicillin and streptomycin. Occasional strains were resistant to neomycin, lincomycin, erythromycin, tetracycline, chloramphenicol and furazolidone but multiple resistance was rare. No strain showed resistance to methicillin. Resistance to penicillin declined from 35% in 1974-75 to 7.1% in 1979. Most strains (1395) were retested to allow induction of penicillinase; 62% produced the enzyme.

The isolation of Salmonella from jejunal and caecal lymph nodes of slaughtered animals

One jejunal and one caecal lymph node were sampled from each of 50 cows, 40 yearling cattle, 25 sheep, 20 lambs and 45 pigs after slaughter. Salmonella, Clostridium perfringens and Staphylococcus aureus, all organisms which cause food poisoning in man, were sought by direct plating methods. The samples were also enriched and cultured for Salmonella. Organisms were cultured from 208 (58%) of the 360 lymph nodes; aerobic plate counts yielded up to 25,000 organisms per gram of tissue, although from most infected samples less than 1000 organisms per gram were cultured. Salmonella was isolated directly from 5% of samples, with counts up to 1,500 per gram. After enrichment Salmonella was isolated from nodes taken from 15 cows, 2 yearling cattle, one sheep and 8 pigs. Cl. perfringens was isolated from the caecal nodes of 2 yearling cattle and 2 pigs; S. aureus was not isolated from any sample. It was concluded that mesenteric lymph nodes may be a significant reservoir of Salmonella for transfer to meat and meat products.